The invention generally relates to a mobile attachment device. More particularly, the invention relates to a drive assembly for a mobile attachment device wherein the drive assembly comprises a torsional coupling to minimize unwanted torsion impact from being transmitted between the mobile attachment device and the motor.
Land clearing and mobile construction devices are used in a wide range of industries for many different purposes. Examples of land clearing devices include mowers, soil conditioners, wood chippers, stump grinders, and brush cutters. Examples of mobile construction devices include sweepers, cold planers, and rock saws. Collectively, land clearing and mobile construction devices are sometimes referred to herein as mobile attachment devices. These mobile attachment devices are typically attachments mounted to a prime mover such as a tractor, excavator, or skid steer loader. Most mobile attachment devices include protruding members such as blades, knives, picks, brushes, cutting tools, hammers, or teeth (collectively, “teeth”) mounted on a shaft which rotates at a high rate of speed to create the force necessary to cut, crush, or sweep material contacting the teeth. In many mobile attachment devices the shaft is rotated by a hydraulic motor which may be powered by the prime mover.
During operation the teeth may encounter different types of material. Some material may be easier to cut and/or crush than other types of material. For example, in some cases the teeth may inadvertently encounter a rock or other solid object which significantly slows down the rotational movement of the shaft. The slowing and/or stopping of the teeth/shaft during operation may cause an impulse load on the hydraulic motor which can damage the motor.
Existing technologies have tried to prevent or minimize impulse loads from being transferred between the shaft and the motor. Some existing devices use belt drives or rubber isolation discs to help absorb these impulse loads to protect the hydraulic motor. The prior art rubber isolation discs comprise a two-piece flange/bearing housing that contains the rubber isolation disc. The rubber disc is combined with the mobile attachment housing by another retaining ring flange. Within the bearing housing are two angular contact bearings, or tapered roller bearings which require a pre-set preload during assembly. The bearing housing is capped with a flange to mount the hydraulic motor. The complexity of this prior art solution assembly leads to higher costs and poor serviceability. Additionally, the rubber isolation disc can deteriorate from exposure to ultraviolet light and time. The rubber isolation disc when absorbing an impact can deflect the rotor causing a reduction of working rotor speed.
There is therefore a need for an improved drive assembly for a hydraulically powered mobile attachment device which helps to minimize or prevent impulse loads from being transferred between the mobile attachment device and the motor.